Snowshoe Mountain Resort

Summary

SYNOPSIS

... Daily chances for showers and storms continue, with the frequency of storms posing concern for localized flooding. Severe storms are possible tonight and again Wednesday night.

NEAR TERM /THROUGH WEDNESDAY/... As of 945 PM Tuesday...

Cleaned up POPs some to better reflect current situation and latest hi-res guidance, but no other major changes made at this time.

As of 1208 PM Tuesday...

Showers and storms, some strong to severe are expected in the near term period. A large low pressure system will continue to meander across the northern plains, sagging south tonight into Wednesday, filling as it does so. Convection across the midwest last night into this morning, should weaken as it continues eastward, but could reinvigorate later this afternoon/evening as it travels eastward towards our area into an increasingly unstable atmosphere, along with additional rounds of storms expected overnight from additional shortwaves crossing the area. Strong cape on the order of around 2000 J/Kg, and increasing shear of 50+ kts, along with curved hodographs and low lcl heights, lead to threats for all hazards, including large hail, and strong damaging winds/downbursts, and perhaps an isolated tornado, although the greater risk for that looks to lie to our west. Period of greatest threat appears to be by 20Z through 03Z.

There may be a bit of a lull in the activity for the first part of Wednesday, but another potent wave will move through the area later Wednesday evening into the short term period, with heavy rains and severe weather potential, although this period damaging winds and hail look to be the primary risks, with a lesser risk for tornadoes, although it cannot be completely ruled out either.

In addition, increasing southwesterly flow across the area should allow for PW values to rise into 1.4 to 1.5 inches today, and approach 1.7 inches on Wednesday, and this with areas of saturated soils from recent days, elected to issue a flood watch for flash flooding across parts of the region. That will include the potential for any convection today, plus additional rounds on Wednesday, and continues into Thursday morning.

SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/... As of 310 PM Tuesday...

A complex, moisture-laden system crosses Wednesday night into Thursday morning.

Ahead of it, a roughly west to east oriented front draped roughly across central portions of the area lifts north Wednesday night. Instability is maximized in an axis along the front and present south of it Wednesday evening, and thunderstorms quickly become possible throughout the area Wednesday night.

Surface low pressure rides along the front, which then reverses course and moves southeastward across the area overnight Wednesday night into Thursday morning. instability along and ahead of the cold front becomes increasing elevated throughout the night time period. However, ample forcing, shear, and moisture convergence keep showers and thunderstorms going through the overnight and into Thursday morning.

Convective parameters peak ahead of the cold front across southern, mainly southwestern, portions of the area Wednesday night, and will largely depend upon how strong a nocturnal low level jet we can develop before the front passes. While there would be more time for this farther east, instability will continue to maximize farther west until the front crosses. A self-feedback mechanism is likely to modulate these factors with MCS development, with large hail, damaging wind and even tornadoes possible across southwest portions of the area after sunset and through about midnight.

PW values peak in the 1.6 to 1.9 range, also dependent upon the strength of the nocturnal low level jet. Nonetheless, with low flash flood guidance getting lower with each round of convection, high rainfall rates are likely amid numerous showers and thunderstorms Wednesday night into Thursday morning, and the Flood Watch for Flash Flooding runs through Thursday morning to cover this scenario.

The thunderstorm threat and associated hazards wane overnight and especially toward dawn Thursday, followed by decreasing coverage Thursday morning, amid a deepening post-frontal/post- MCS inversion.

A trailing mid-upper level short wave trough and reinforcing cold front, and diurnal heating, may bring one more uptick in showers and thunderstorms Thursday afternoon into Thursday evening, but the thunderstorms should be far less impactful this time given far less CAPE and lower echo tops. The weather dries out but remains cloudy Thursday night as the second front then reinforces the low level frontal inversion in its wake.

Central guidance reflects a mild, well above normal night Wednesday night, and highs Thursday tempered by the post-MCS environment, but still above normal. Lows get closer to normal for Friday morning behind the second cold front.

LONG TERM /FRIDAY THROUGH TUESDAY/... As of 140 PM Tuesday...

The weather remains active but nowhere near as impactful in the long term, compared with the near and short term periods.

Friday morning finds the area in west to northwest low level flow between low pressure off to the northeast and moving away to the northeast with its associated mid-upper level short wave trough, and surface high pressure approaching from the west.

There is another mid-upper level short wave trough that crosses Friday afternoon, but models evince that enough low level cool air comes in behind the cold front to create an unbreakable mid level inversion 6 kft agl south to 12 kft agl north. Thus, only low top showers are anticipated, with no hail or impactful wind gust threat even where if we do manage charge separation.

The weather dries out Friday night as the high ridges in from the southwest. However, another mid-upper level short wave trough and surface low intercept that ridging as they pass north of the forecast area Saturday afternoon and evening. This gives rise to the chance for mainly afternoon and evening showers and perhaps thunderstorms in the mixed layer below the inversion which, at this point, can be eroded.

Another short wave trough pivots through Sunday afternoon, all this around evolving broad mid-upper level low pressure over eastern Canada, again with the mainly afternoon chance for showers and perhaps a thunderstorm. The mid-level inversion manifests as just a less steep lapse rate layer, but it and dry low level air limit CAPE and keep it narrow.

We may manage daytime dry whether at times early next week depending upon timing of frequent but weak weather systems moving through.

Central guidance reflects below normal temperatures Friday and this weekend, before climbing back to and eventually above normal early next week, as mid-upper level ridging tends to build amid the weak systems.